FIG. 1 is a view of a portion 10 of a sea surface 12 in which several platforms in the form of ships are disposed. In FIG. 1, a flotilla 14 of friendly ships includes ships 16, 18, and 20. As described in U.S. patent application Ser. No. 12/199,082, filed on or about Aug. 28, 2008 in the name of Bergman, and entitled METHOD FOR TRANSMISSION OF TARGET INFORMATION OVER A NETWORK (GE-07331), ships 16, 18, and 20 each bear sensors, such as radar, infrared sensors, optical sensors, or the like, designated generally as 21, which sense the presence of the other ships of flotilla 14, and which also sense the presence of other targets in the vicinity, represented by an aircraft 22. Those skilled in the art know that the term “target” merely identifies an object and does not suggest that action is taken against the object. The sensing of aircraft such as 22 by the ships of flotilla 14 is represented in FIG. 1 by “lightning bolt” symbols 24 and 26. The ships 16, 18, and 20 of flotilla 14 communicate among themselves by means of a communication network N, inter-ship portions of which are designated by lightning bolt symbols N1, N2, and N3. Such networks are sometimes known as “tactical” networks. It should be understood that the interplatform or intership network N may include many different signal paths, which variously include digital and analog portions, portions which are encrypted and other portions of which are not encrypted, and which traverse various paths, possibly including a path (not illustrated) extending through a satellite 36.
Each of the sensors of ships 16, 18, and 20 of flotilla 14 makes its own assessment of the sensor signals which its own sensors generate, and digitally distributes the assessed information (or possibly some raw information from some sensors) over an ownship or onboard network (not illustrated in FIG. 1) and also over the network N among the ships of the flotilla 14. Thus, each ship of flotilla 14 nominally has access to all the information from the various ships of the flotilla.
From the location of flotilla 14 of FIG. 1, a hostile ship 30 is over the horizon, and therefore may be invisible to the sensors of the flotilla 14. A friendly ship 32 is illustrated as being in the general vicinity of hostile ship 30, sufficiently so that its sensors can sense the hostile ship, as suggested by lightning bolt 34. Friendly ship 32 also senses aircraft 22 as represented by lightning bolt 38.
The sensors of the various ships of flotilla 14 of FIG. 1 produce data at a prodigious rate. Radar systems, for example, may recurrently scan hundreds of square miles of surface and the volume above it, producing data, possibly at a rate in the hundreds or thousands of megabytes per second. Sonar systems and infrared sensors may also produce large amounts of data. All of these sensors produce data even when there are few targets, and produce the data at even greater rates in a target-rich environment. Even though the inter-ship network N of FIG. 1, including at least paths N1, N2, and N2, has a finite bandwidth and must handle traffic other than sensor data, vast amounts of target data may arrive at each ship from the network. As mentioned, each ship may have its own sensors. Consequently, each ship receives large amounts of information even if only from its own sensors, and this amount of information can only increase when sources external to the ship provide their data.
One conventional way to moderate the information traversing the inter-ship network N is for the operator of the radar or other sensor to “turn off” one or more targets or categories of targets. For example, in the presence of a great deal of sensor data, he may “turn off” the friendly targets, so that data pertaining to targets deemed friendly is or are not transmitted over the network. Another possibility is to turn off transmission of data pertaining to commercial airflights, as not being of immediate interest. Other classes of targets, or specific targets, can be identified for non-transmission over the network. It will be appreciated that it is possible for targets previously deemed to be friendly to later be determined to be hostile, but the blocking of data transmission may inadvertently continue.
The Bergman patent application describes an arrangement for throttling inter-ship transmissions by transmitting data relating to friendly targets or tracks at lower rates than data relating to hostile targets, or in response to proximity of a hostile target to a friendly asset, or by the ability of a recipient to determine position from old data.
Notwithstanding any limitations on the bandwidth of inter-platform communications, each platform will continue to receive large amounts of target track and other data. In general, different ships within a flotilla will have different assigned missions, and as a result they will have different target track data needs. For example, ships assigned to counter threats from air objects such as enemy airplanes and/or missiles will have a greater need for data concerning airborne target tracks than ships assigned to minesweeping duties, which ships will be more concerned with surface and sub-surface target tracks. Furthermore, different systems on the same ship are assigned for use in different functions, and such different systems on a single ship will, in general, have needs for different types of target track data. It will be appreciated that some onboard systems may be designed to be able to handle very large information flows. Handling such large information flows may be important to the system function, as for example in the case of overall situation analysis determination, and in the case of hostile boosting or ballistic missile detection, path analysis and engagement with interceptor missiles, guidance of the interceptor missiles toward the hostile missile, and generally enabling ownship to constructively participate in the battle group and perform its assigned tasks. In FIG. 1, the hostile ballistic missile is illustrated as 40, and an interceptor missile is illustrated as 42. There will be other shipboard systems, however, which do not need as much of the sensor data to accomplish their functions. Such other systems may include, for example, undersea warfare systems, which generally do not analyze flying objects.
Improved arrangements for handling data are desired.